Police are unlikely to build a case against former coaches of Nihon University's American football team over their alleged instructions to a player to commit a dangerous tackle, finding no evidence to support the allegations, investigative sources said Tuesday.

Former head coach Masato Uchida, 63, and former assistant coach Tsutomu Inoue, 29, have been questioned by the police on a voluntary basis over a possible case of assault during an intercollegiate game in May. The focus has been on whether their instructions carried the intent to injure the opponent as perceived by the Nihon University player.

(Kwansei Gakuin University quarterback Kosei Okuno, right, plays in a game against Kansai University in Suita, Osaka Prefecture, on May 27, 2018, his first since suffering injuries in a dangerous late tackle during an intercollegiate game against Nihon University on May 6)

During rare police investigations over such foul play, investigators also studied the statements of Taisuke Miyagawa, 20, who injured a Kwansei Gakuin University quarterback through the violent tackle, and more than 200 players and other people involved.

They also analyzed images of the game in question and judged there is no evidence to determine that the instructions could be deemed unlawful, the sources said.

The police also decided that a remark such as "crush the quarterback," which Inoue admitted to having told Miyagawa, can be used in general to mean "tackle strongly" and does not necessarily amount to an instruction to injure an opponent.

(Former Nihon University American football head coach Masato Uchida, right, and assistant coach Tsutomu Inoue at a press conference in Tokyo on May 23, 2018)

Miyagawa is expected to be referred to prosecutors for alleged assault, but the injured quarterback Kosei Okuno, who has filed a criminal complaint against Uchida and Inoue, is seeking leniency for Miyagawa himself.

The two athletes have reached an out-of-court settlement.

Miyagawa told a press conference on May 22 that he had followed the instructions of the coaches in tackling Okuno from behind after Okuno had already finished throwing the ball, a claim refuted by the two, who said Miyagawa misinterpreted their instructions.

The Kantoh Collegiate Football Association, the governing body of college American football in Tokyo, concluded through its own investigation that the two coaches ordered the foul play and expelled them in June. The two have appealed the lifetime ban.

Nihon University announced the dismissal of Uchida and Inoue as employees of the university in July following their resignation from their coaching roles in May in the wake of the incident, which stirred controversy nationwide despite American football being a minor sport in Japan.

Miyagawa returned to the team and resumed training in October.